creat(2) System Calls Manual creat(2)
Name
creat - create a new file
Syntax
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <limits.h> /*Definition of OPEN_MAX*/
creat(name, mode)
char *name;
mode_t mode;
Description
The system call creates a new file or prepares to rewrite an existing file called name, given as the address of a null-terminated string.
If the file did not exist, it is given mode mode, as modified by the process's mode mask. For further information, see Also, see for the
construction of the mode argument.
If the file did exist, its mode and owner remain unchanged, but it is truncated to zero length.
The file is also opened for writing, and its file descriptor is returned.
The mode given is arbitrary; it need not allow writing. This feature has been used in the past by programs to construct a simple exclusive
locking mechanism. It is replaced by the O_EXCL open mode, or facility.
No process may have more than OPEN_MAX files simultaneously.
Return Values
The value -1 is returned if an error occurs. Otherwise, the call returns a non-negative descriptor that permits only writing.
Environment
Differs from the System V definition in that ELOOP and ENXIO are possible error conditions, but ENFILE and ENOSPC are not.
Diagnostics
The system call fails and the file is not created or truncated under the following conditions:
[ENOTDIR] A component of the path prefix is not a directory.
[EACCES] Search permission is denied for a component of the path prefix.
[EACCES] The file does not exist, and the directory in which it is to be created is not writable.
[EACCES] The file exists, but it is unwritable.
[EISDIR] The file is a directory.
[EMFILE] Too many files are open.
[EROFS] The named file resides on a read-only file system.
[ENXIO] The file is a character special or block special file, and the associated device does not exist.
[ETXTBSY] The file is a pure procedure (shared text) file that is being executed.
[EFAULT] The name points outside the process's allocated address space.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[EOPNOTSUPP] The file is a socket, which is not implemented.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire pathname exceeded 1023 characters.
[ENOENT] The named file does not exist.
[ENFILE] The system file table is full.
[ENOSPC] The directory in which the entry for the new file is being placed cannot be extended, because there is no space left on the
file system containing the directory.
[ENOSPC] There are no free inodes on the file system on which the file is being created.
[EDQUOT] The directory in which the entry for the new file is being placed cannot be extended because the user's quota of disk blocks
on the file system containing the directory has been exhausted.
[EDQUOT] The user's quota of inodes on the file system on which the file is being created has been exhausted.
[EIO] An I/O error occurred while making the directory entry or allocating the inode.
[ESTALE] The ``file handle'' given in the argument is invalid. The file referred to by that file handle no longer exists or has been
revoked.
[ETIMEDOUT] A connect request or remote file operation failed because the connected party did not properly respond after a period of
time that is dependent on the communications protocol.
See Also
close(2), chmod(2), open(2), umask(2), write(2)
creat(2)